Since the days of the colonists, maple syrup and sugar have been manufactured by tapping maple sap from sugar maple trees in late winter, and applying heat from an open fire or confined flame against the bottom of a vaporizer tank or tub within which the maple tree sap is placed to concentrate the sap and develop maple syrup. Typically, there is a high loss of heat resulting from the combustion of wood, coal or liquid hydrocarbon fuel, both by radiation, thermoconduction and by the heat carried within the exhaust gas which may escape through a vertical flue or chimney associated with the apparatus. Since the advent of fuel shortages such as the liquid hydrocarbon fuels, more attention has been paid to developing an effective furnace apparatus for heating the overlying vaporizing pan or pans and the concentration of developed heat from burning of the fuel, against the bottom surface of the vaporizing pan or pans and improving the combustion process to maximize the heat resulting from the combustion of a satisfactory fuel/air mixture.
In an effort to improve the overall efficiency of the maple syrup vaporizer apparatus, in the very recent years, there has been developed a piggy back type vaporizer pan assembly in which the water vapor which is boiled off the maple tree sap within the primary vaporizing pan, is condensed on a sheet metal drip pan overlying the primary vaporizing pan and which heat, in turn, is supplied by conduction to sap or syrup in the secondary vaporizing pan positioned immediately above the main vaporizing pan.
While such efforts have been helpful, there is a need for a unitary maple syrup vaporizing apparatus consisting of one or more end to end positioned vaporizing pans and an underlying furnace or arch which is purposely configured to reflect generated heat in the direction of the overlying pans, which effectively directs the combustion gases along a path in direct contact with the overlying end to position vaporizing pans, which effectively reduces the waste heat leaving with the exhaust gases by regenerative heating of the incoming fresh air employed in combustion of the fuel within the furnace section of the unitary apparatus, and in which the combustion products are forced along a reversible recirculation path prior to entering the chimney thereof.